The present invention generally relates improvements in portable power tools, and more specifically to improvements that are particularly well suited for use with wood working power tools such as portable power planers.
Various power tools are used in woodworking in an effort to efficiently and accurately form workpieces to desired dimensions and with a desired surface finish. As is widely known, planing machines are often used for surface planing of wooden boards. A conventional planing machine typically includes one or more rotatably mounted cutting blades attached to a vertically movable carriage assembly. Also known are jointer machines which are typically used for the edge planing of wood. In certain applications, the functions of conventional planing machines and jointers are combined within a single unit commonly referred to as a jointer/planer machine.
In a typical wood planing machine, such as a surface planer, a selectively adjustable workpiece opening is defined between a carriage assembly and the planing surface of the base of the machine. The rotationally mounted blades are carried on the underside of the carriage assembly adjacent to the workpiece opening. The blades are adapted to remove a predetermined amount of material from the workpiece depending on the thickness of the workpiece and the height of the workpiece opening. The carriage assembly also usually includes one or more feed rollers which urge the workpiece through the workpiece opening during the operation of the wood planing machine.
In most applications, the carriage assembly of a wood planing machine is movably mounted to a plurality of support columns for movement with respect to the planing surface. Such movement of the carriage assembly adjusts the vertical dimension of the workpiece opening so as to selectively determine the amount of material to be removed from the workpiece. Alternatively, the carriage assembly may be fixed and the planing surface adjusted vertically with respect to the carriage assembly so as to adjust the vertical dimension of the workpiece opening.
In use, a workpiece is passed through the workpiece opening and a predetermined amount of material is removed from the surface of the workpiece adjacent the carriage assembly. Multiple passes of the workpiece through the workpiece opening are often necessary to obtain the desired thickness and surface finish. As with other woodworking operations, it is desirable that a planing machine accomplishes preparation with precision, repeatability and a high quality surface finish. In order to accomplish these goals, many of the planing machines of the prior art have relied on designs that utilize rather large and heavy components.
While such designs have proven to be acceptable for relatively large planing machines which are repositioned on a relatively infrequent basis, they have largely been inadequate for portable planing machines, due to their weight. Accordingly, there is a need in the art for a portable planing machine having a highly robust design that permits a workpiece to be prepared with precision, repeatability and a high quality surface finish.
In one preferred form, the present invention provides a power planer having a base with a reference surface; a carriage assembly; and a carriage elevation mechanism. The carriage elevation mechanism includes a plurality of guide posts that include a threaded adjustment portion and which are fixedly coupled to one of the base and the carriage assembly. The carriage elevation mechanism also includes an elevation mechanism with a plurality of threaded structures, each of the threaded structures being threadably engaged to the threaded adjustment portion of an associated guide post. Each threaded structure is coupled to the other one of the base and the carriage assembly such that rotation of the threaded structures relative to the guide posts affects an elevation of the carriage assembly relative to the reference surface.
In another preferred form, the present invention provides a power planer having a base, a carriage assembly, a carriage elevation mechanism and a locking mechanism. The carriage elevation mechanism includes a plurality of guide posts, each of which being fixed to the base and having a threaded adjustment portion, and a plurality of nut assemblies. Each of the nut assemblies is coupled to the carriage assembly and threadably engaged to the threaded adjustment portion of an associated one of the guide posts. Each nut assembly includes a first threaded structure and a second threaded structure, which are coupled to one another for common rotation but movable in an axial direction relative to one another. The locking mechanism may be selectively positioned in a disengaged condition, which does not inhibit in-unison rotation of the first and second threaded structures, and an engaged condition, wherein the first threaded structure is moved axially relative to the second threaded structure to lock the threaded structure against the threaded adjustment portion of the associated guide post and thereby inhibit in unison rotation of the first and second threaded structures.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.